颜色直方图opencv c++代码

颜色直方图比较简单，统计图像中的颜色分布。是个常用的全局特征，一般需要的话，可以加上SPM，能有效对空间位置进行编码。

代码如下：

#include 
#include 
#include "opencv2/core/core.hpp"
#include "opencv2/highgui/highgui.hpp"
#include "opencv2/nonfree/features2d.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include 
using namespace cv;
using namespace std;

void compute_colorfeatures(const string& imgPath, vector& features) {
        Mat mat = imread(imgPath);
        Mat hsv_img;
        cvtColor(mat, hsv_img, COLOR_BGR2HSV);
        int h_bins = 30;
        int s_bins = 50;
        int histSize[] = { h_bins, s_bins };
        // hue varies from 0 to 256, saturation from 0 to 180
        float s_ranges[] = { 0, 256 };
        float h_ranges[] = { 0, 180 };
        const float* ranges[] = { h_ranges, s_ranges };
        // Use the o-th and 1-st channels
        int channels[] = { 0, 1 };
        /// Histograms
        MatND color_features;
        /// Calculate the histograms for the HSV images
        calcHist(&hsv_img, 1, channels, Mat(), color_features, 2, histSize, ranges,
                        true, false);
        normalize(color_features, color_features, 0, 1, NORM_MINMAX, -1, Mat());
        for (int i = 0; i < color_features.rows; i++) {
                for (int j = 0; j < color_features.cols; j++) {
                        features.push_back(color_features.at(i, j));
                }
        }
}